Ventilated resistor



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C. C. WHITTAKER VENTILATED RESISTOR Filed April 1l, 1941 A July e, 1943.

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Patented July 6, 1943 UNETED STATES PATENT OFFICE 2,353,743 VENTELATEDRESISTGR Charles C. Whittaker, Pittsburgh, Pa., assigner to WestinghouseElectric & Company, East Titt'sliur of I ennsylvania Manufacturing gh,Pa., a corporation Application April 11, 1941, Serial No. 388,058 13Claims. l (Cl. 24H-174) My invention relates, generally, to resistorsand A further object of my invention is to provide x for more rapidlydissipating heat from a resistance element of the edge-wound type so asto permit a relatively small resistance element to handle safely largeamounts of power.

Another object of the invention is to utilize internal core members andexternal baffle members with. resistance elements of the edge-Wound typeto provide a plurality of ducts between the adjacent turns of theelements which present relatively low resistance to the flow of acooling medium.

Another object of my invention is to provide for supporting a resistanceelement of the edgewound type by baiiie members on each side oi theelement which function to direct the flow of a cooling medium betweenadjacent turns of lthe element.

Still another object oi my invention is to pro'- vide for supporting aplurality of edge-wound l resistance elements in spaced relation bymeans oi' baille members positioned between the elements tosubstantially l the space therebetween and direct cooling medium betweenthe adjacent turns oi the elements.

4 A further object of my invention is to provide for mechanicallyinterlocking a plurality of re- Other objects will in part be obvious,and will in part be explained hereinafter.

My invention provides a highly eiiicient ventilated resistor forapplication Where the amolint of power to be handled is large 'and thespace available is small without the danger of excessive heating. Inpracticing the invention in a preferred form, the resistance elementsmay each comprise a plurality of turns of a ribbon of suit, 55

able resistance material wound on edge in a generally helical shape.Refractory core members are positioned within the element and providedwith spaced ribs er projections for supporting the turns in spacedrelation, and baille members of a refractory material are positionedbetween the adjacent elements to substantially nll the spacetherebetween. The baille members are provided with enlarged end portionsonthe with the cere members a plurality of ducts be- 'lhe resistor isor" the resistor unit shown in Fig. 1;

Fig. 3 is an enlarged plan View of the resistor shown in the resistorunit of Fig. 1;

Fig. 4 is an enlarged vertical sectional View along the line IV-IV ofFig. 3;

Fig. 5 is a front elevational View of a modified form oi resistorembodying the principles of the invention;

Fig. 6 is a sectional view taken along the-line Fig. 7 is an enlargedpartial view in section taken along the line VIIVII of Fig. 5;

Fig. 8 is an enlarged partial View in section taken along line VIII-VIIIof Fig. 5; and

Fig. 9 is an enlarged partial vView in section taken along the lineIX-IX of Fig. 6.

Referring to Figs. 1 and 2, the reference numeral I0 may denote,generally, a ventilated resistor unit comprising a resistor I2, whichmay be positioned within an enclosure I3 and 4provided With Ventilatingmeans such as the blower I4 for directing a cooling medium such as airtherethrough.

The enclosure I3 may be of any suitable construction, comprising, forexample, a frame structure I5 having partitions I6 with openings I1therein, positioned intermediate the top and bottom to divide theenclosure into sections. The upper section may be enclosed at the sidesby means of suitable side panel members I8, and provided with an openingI9 at the top. The resistor I2 may be supported in the upper section inany suitable manner, such as by means of bracket members 20 secured tothe frame structure.

The blower I4 may be positioned between the partitions I6 and theopenings I1 therein utilized as inlets and outlets therefor'. The blowerI4 may be driven by a motor 2I, which may be mounted in the lowersection of the enclosure and connected to the blower by a belt 22. Thecentral and lower sections of the enclosure I3 may be provided withperforated side panel members to substantially enclose the motor andblower, and provide for the ingress of air to the resistor. A suitableterminal board 24 may be mounted adjacent the resistor for makingconnections thereto.

Referring to Figs. 1, 2, 3 and 4, it will be seen that the resistor I2may comprise a plurality of elongated resistance elements 25, supportedbetween end frame members 25 of insulating material by means of tie rods21, which may be connected to the bracket members 20. Side frame members28 may be secured between the end frame members 26 by means of angles 29to substantially enclose the elements on all sides.

The resistance elements 25 may comprise spaced turns 3l) of a ribbon ofsuitable resistance material wound edgewise and generally helical inform. While the elements are shown as having circular sections, it willbe understood that they may have other sections, such as oval orflattened circular sections without departing from the scope of theinvention. Core members 32 of refractory material having serratedsurfaces may be positioned within the elements to maintain the turns inspaced relation. The core members may be mounted on the elongatedsupport bars 34, which may be provided with slots 35 on the innersurfaces to receive the bars. The ends of the bars may be provided withslots 36, as shown in Fig. 2. to receive the tie rods 21 andy supportthe bars thereon. Tubular spacers 38 may be positioned on the tie rods21 between the support bars 34 to maintain the elements in spacedrelation.

In order to provide for cooling the resistor elements 30 in a mostefficient manner. suitable means, such as the baille members 40 may bepositioned between the adjacent elements to substantially fill thespaces therebetween and force the cooling medium to pass directlybetween the adjacent turns of the elements. The baille members 46 may bemade of any suitable refractory material capable of withstandingrelatively high temperatures, and may be positioned between the adjacentelements in any suitable manner. For example, opposite sides 4I of thebaille members 40 may be dished transverse to the longitudinal axis ofthe element, as shown, conforming, generally, to the curved edgeportions of the elements 25. The baffle members will, therefore. havesubstantially dumbbell shaped sections which are narrower in the midportion and wider adjacent the ends. When the baille members arepositioned between the adjacent elements, the enlarged end portions 42mechanically interlock with the elements and prevent movement of thebaffle members transverse to the longitudinal axis of the elements, thussecurely positioning them therebetween. If desired, the baille members4D may be provided with projecting ribs 43 along the front and backedges of the dished surface portions so that direct contact with theresistance elements may be made by means oi the projecting rib portions,thus making it easier to align the baffle members with the resistanceelements, since the area of contact therebetween is thus greatlydiminished and variations of dimensions in manufacturing are renderedless material.

Referring to Figs. 5 through 9 of the drawings, the reference numeral 45designates, generally, a mcdiiied form or resistor wherein a pluralityof resistance elements 45 comprising spaced turns 41 of a ribbon ofresistance material wound on edge may be supported between the end framemembers 48 by means of a plurality of refractory baille members 5D,secured to the end frame members by means of tie rods 5I.

As shown in Fig. 7, the resistance elements 46 may be supported onelongated metallic support bars 52 by means of refractory core members53 positioned on the opposite edges of the support bars. The coremembers 53 may be provided with serrated surfaces so as to formprojecting linger portions 54 at spaced intervals which may bepositioned between the turns of the resistance element to retain them inspaced relation.

The end frame members 48, which may be of a suitable insulating materialsuch as, for example, asbestos board, may be provided with a pluralityof transverse slots 55 having recessed portions 56 adjacent the centralportion of the end frame for receiving the ends of the support bars 52.Suitable openings 51 may be provided in the end frames in alignment withthe slots 55 to receive terminals 58, which may be provided with anenlarged head portion 59 having a projecting rib 6I) adapted to bepositioned in the slot 55 to prevent the terminal from turning. Theresistance elements 46 may be connected to the terminals 58 in anysuitable manner, such as, for example, by means of the welds 60.

In order to provide for directing a cooling medium between the adjacentturns of the resistance elements 45, and for also supporting theelements, the baffle members 50 may be provided with surface portions 62on the opposite sides thereof conforming, generally, to the curvature ofthe outer edges of the resistance elements and rounded end portions 63on the front and back having substantially greater width than themidportion oi" the baille member, as shown in Fig. 9. Suitablelongitudinal openings 66 may be provided through the enlarged endportions of the baille members to receive the tie rods 5I and tubularspacing members 66, which enable the nuts 61 on the tie rods to be drawntight without applying excessive pressure to the baffle membersthemselves.

Since the baille members 50 which are positioned between the adjacentresistance elements 46 have a substantially dumbbell shaped section,pockets are, in effect, provided between the adjacent balile members forreceiving the resistance elements. Because of the enlarged end portionsof the baille members, the resistance elements are securely locked inposition between the adjacent baille members. which not only provide fordirecting a smooth and uniform flow of cooling medium between the ducts,thus formed between the adjacent turns of the resistance elements andthe baille and core members, but also assist in positioning andsupporting the resistance elements.

Since the `elements are effectively .supported throughout their lengthby the baille members 5B, vthe elements may be made much longer thanusual, vwithout any danger of sagging. The resistor of Figs. 5 through 9is shown as having a single row of resistor elements. Such a resistor'may be used in applications where only a relatively loW pressure isavailable for forcing the cooling medium therethrough. Where greaterpressures are available and greater capacity is needed, such units maybe arranged in tandem as desired.

From the .above description and the accompanying drawings, it will beapparent that I have provided a simple and efficient ventilated resistorvwherein the baille members, which are interloclred Awith the resistanceelements, may be supported Vby o1' may themselves support the resistanceelements. A smooth, non-turbulent flow of a cooling medium may thus beconfined tothe immediate space between the adjacent of the resistanceelements so that efficient cooling the elements may be secured andrelatively large kamounts of power may be handled with a rele.-

tively small resistor requiring only a relatively low pressure to forcethe cooling medium through the cooling ducts.

By utilizing with resistors of the edge-wound type baille members Aofthe type l have hereinbefore described, whereby the resistance elementand baille member are mechanically interloclied, much greater heatdissipation may be secured vfrom a given length of resistance t-.an waslie etofore possible.

With the arrangement shown 5 through 9, the resistance elements besafely operated at much higher temperatures `than heretofore withoutfear of sagging. In addition, longer elements may be used, since thebaille members interlock therewith and support the elements, since thepath of the or other cooling medium is limited the baille members tosubstantially the between the turns of the elements. For a given volumeef air, more than .ten times the usual heat dissipation secured merelyblowing air between the elements may be obtained by utilising thearrange- .ent embodying my invention,

.Since different embodiments of the invention may be made.. and changesmade in the rawi -s and above description without departing from thespirit thereof, it is intended that all matter centained in the abovedescription or shown in the accompanying drawings shall be considered asillustrative, and not in a limiting sense.

I claim as my invention:

1. A resistor comprising elongated core member of insulating material, aresistance element including a plurality of spaced turns of an edgewisewound ribbon of resistance material of generally helical form positionedabout the core member, and a pair of elongated baffle members ofinsulating material so positioned on opposite sides of the element andhaving transversely curved surface portions in juxtaposition to theouter edges of the turns o-f the resistance material so shaped as todenne with the core member a plurality of relatively long arcuatechannels between adjacent turns of the element throughout substantiallythe full length of the element.

2. An elongated resistance element comprising, an edgewound ribbon ofresistance material formed generally into a helix, a core memberpositioned within the element, and an elongated baille member positionedon each side of the reysistance element `having :a 'longitudinal grooveconforming generally to the outer portion of ative movement of theelement and baille member .in a direction transverse to the longitudinalaxis of the element.

3. Aresistor comprising, a generally helical resistance element having aplurality of spaced turns of resistance ribbon Wound on edge, arefractory core member positioned within the element, and a pair ofelongated =baille members positioned on opposite sides of the elementhaving transverse curved surface portions positioned in engagement withthe outer edges of the turns vthereof cooperative with the core memberand the turns of the resistance ribbon to define a plurality ofrelatively long open ducts conned between the adjacent turns for acooling medium throughout substantially the `length of the element.

4. The combination with a resistor having an elongated resistanceelement comprising ya plurality of edgewise wound turns of ribbon ofresistance material positioned in spaced relation .on a core member, ofa pair of elongated refractory baille members having surface portionsconforming generally to the Vconteur of the outer edges of the turns ofthe element transversely and contiguous therewith throughoutsubstantially the length of the element positioned on opposite sides ofthe element to partially enclose the element and define with the coremember a plurality of arcuate ducts between the adjacent turns from oneside of the element to the other.

V5. A .resistor comprising, a frame, an edgewound resistance elementhaving spaced turns of resistance ribbon of generally helical shape, arefractory core member positioned within the element having a pluralityof spaced teeth between the turns of the element, and refractory memberssupported in the frame having surface `portions conforming .generally toand engaging the outer edge portions of the element through- -outsubstantially the length of the element positioned in opposed relationon opposite sides of the element to secure the resistance elementtherebetween and to denne a plurality of ducts .between and bounded bythe turns of the element for ra cooling medium.

6. The combination in a resistor, of a plurality of elongated resistanceelements comprising spaced turns of a ribbon resistance material woundon edge, a core member positioned Within each element and connected to asupporting frame, and baille members positioned in substantially4continuous end to end relation between Yadjacent elements having curvedsurface portions .conforming substantially to the adjacent portions ofthe element shaped to define with the core member a plurality of arcuateducts of substantially the width of the ribbon from one side of theelement to the other and enlarged end portions on opposite sides of theelements projecting inwardly to partially enclose the elements andinterlock mechanically in a transverse direction with the said elements`to provide a substantially continuous baille throughout the length ofthe elements and to retain the baille members in end to end relationbetween the elements.

7. The combination with a resistor having a plurality of elongatededgewound resistance elements with a plurality of turns of ribbonresistance material wound on edge and positioned on core memberssupported in a frame, of a plurality of baiiie members having generallydumbbell shaped sections with opposed surfaces conforming generally tothe outer edges of the turns of adjacent elements to define with thecore member relatively long arcuate ducts of substantially the width ofthe ribbon from one side of each element to the other and enlargedportions on opposite sides of the elements positioned between adjacentelements to interlock mechanicallly therewith and secure the baiiiemembers between the elements.

8. A resistor comprising, a plurality of elongated resistance elementshaving a plurality of spaced edgewound turns of ribbon resistancematerial, a plurality of core members having spaced nger portionspositioned within the elements to maintain the turns thereof in spacedrelation, a frame structure, and a plurality of bailie members extendingsubstantially continuously throughout the length of the elementspositioned between the elements and supported by the frame structurehaving recesses on opposite sides to receive and partially enclose theouter edges of the turns, whereby said baiile members support theelements between adjacent bafe members l,

against movement transverse to the longitudinal axis of the elements anddene a plurality of ducts between the turns thereof.

9. A resistor comprising, a plurality of resista-nce elements comprisinggenerally helical edgewise formed spaced turns of a ribbon resistancematerial, a frame, means including refractory core members positionedwithin the elements to support them in spaced relation in the frame, anda plurality of refractory baie members positioned in juxtapositionbetween adjacent elements having opposing surface portions substantiallycontiguous with the outer edges of the turns of the adjacent elementsshaped to define with the core member arcuate ducts between adjacentlturns for a cooling medium and enlarged end portions on each side ofthe elements having a width greater than the space between adjacentelements to interlock mechanically with the elements and secure thebaille members relative to the frame.

10. A resistor comprising, a plurality of elongated resistance elementspositioned in spaced relation with openings therebetween and havingedgewise formed spaced turns of a ribbon of resistance material, a coremember positioned within each element having spaced projections on theouter edge positioned between the turns to maintain them in spacedrelation, a frame having spaced end members, a plurality of refractorysupport members positioned in the openings between adjacent elementshaving surface portions adjacent the elements throughout the length ofthe elements conforming generally to the outer edge portions of theelements to provide substantially enclosed ducts between the turnsthereof in a direction substantially transverse to the longitudinal axesof the elements for a cooling medium and restricted portions betweenadjacent elements with enlarged end portions on the front and back sidesof the openings between the elements partially surrounding the elementsso as to interlock mechanically with the elements and position them inthe frame, and means connecting the end members operative to secure thesupport members in the frame.

11. A resistor comprising, a plurality of spaced apart resistanceelements of a ribbon resistance material wound on edge in a generallyhelical shape with spaced turns, a core member positioned within eachelement having projecting portions to retain the turns thereof in spacedrelation, a plurality of baffle members having generally dumbbell shapedsections positioned between adjacent elements to interlock mechanicallytherewith and provide ducts between the adjacent turns of the elementsfor a cooling medium, end frame members, rigid connecting means securingthe end frame members in spaced relation effective to secure the baiilemembers to the end frame members, and terminal members connected to theresistance elements mounted on the end frame members.

12. A resistor comprising, an elongated edgewound ribbon resistanceelement of generally helical form, a plurality of refractory coremembers positioned within the element having surface recesses to receivethe turns to maintain them in spaced relation and an elongated metalsupport positioned within the refractory core members, a terminalsecured to an end of the element having a headed stem with a projectingrib on the stem side of the heady an end frame member having atransverse slot to receive an end of the elongated metal support and theprojecting rib of the terminal, a pair of refractory baille memberspositioned on opposite sides of the element having surface portionsadjacent the element conforming generally to the outer edges of theturns of the element and enlarged front and back end portionsinterlocking mechanically with the element, and means to secure thebaiile members to the end frame member with the element therebetween.

13. A resistor for use with means for producing forced ventilationcomprising an elongated resistance element having a plurality of spacededgewise wound turns of a ribbon resistance material positioned on acore member and supported in a frame, of a baiile member extending alongeach side of the element throughout the length thereof having alongitudinal groove to receive the outer portions of the element shapedto define relatively long and narrow ducts bounded by the turns of theribbon and interlock mechanically therewith in a transverse direction.

CHARLES C. WHITTAKER.

